The Impact of Calving Distribution on Weaning Weights in Spring and Fall Calving Herds
Applied Research
John Benner
Extension Agent
Virginia Cooperative Extension
Verona
Abstract
Calving distribution is defined as the proportion of females in a beef cattle herd calving within 21-day periods (approximate length of estrus cycle) of the calving season. Cows that calve in the first 21 days of the calving season are generally bred earlier in the breeding season and raise calves that are heavier at weaning. Calving and weaning data from the Virginia Tech Shenandoah Valley Agricultural Research and Extension Center/McCormick Farm (SVAREC) beef cattle herd from 1999-2023 was analyzed. These records included 2,072 spring born calves and 1,670 fall born calves (total=3,742). Mature Cow records were separated from first calf heifer records to be analyzed separately as recommended by previous research (Cushman, 2012; Funston, 2013) and as the breeding season for cows and heifers did vary slightly. Spring calves born to first calf heifers that calved in the first 21 days of the calving season were 45 lbs heavier (P<0.05) at weaning than calves born in the second 21 days of the calving season. Spring calves born to mature cows (aged 3 yr old+) in the first 21 days of the calving season weighed 39 lbs greater (p<0.05) than calves born in the second 21 days and 90 lbs more than those born in the third 21 days (p-value<0.05). Fall calves born to first calf heifers in the first 21 days of calving season averaged a weaning weight 38 lbs heavier (P<0.05) than calves born in the second 21 days. Fall calves born to mature cows (aged 3 yr old+) in the first 21 days of the calving season weighed 68 lbs (P<0.05) more than calves born in the second 21 days of the calving season and 145 lbs more than calves born in the third 21 days at weaning (P<0.05). To improve calf crop weaning weights, uniformity, and marketability, producers should strive to ensure that females are bred early in the breeding season to increase the percentage of calves born early in the calving season, thereby increasing calf weaning weights through an age-advantaged calf.
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Authors: John Benner, Gabe Pent
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Benner, J. Extension Agent, Virginia Cooperative Extension Augusta County, Virginia, 24482
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Pent, G. Superintendant, Shenandoah Valley Agricultural Research and Extension Center, Virginia, 24472